In the laboratory, test tubes or the like are most often supported in a test tube rack. The test tube rack is a support structure having a plurality of openings extending therethrough for supporting a plurality of test tubes in an upright position. The test tubes are used as extraction containers wherein solutions are added to the tubes and analytes are extracted from the aqueous into organic solvents and visa versa. Occasionally heat of solution occurs and expansion of liquids takes place within the tubes. Often this is facilitated by placing the rack supporting the test tubes in a shaking device. The tubes must be transferred to a centrifuge bucket for separation of phases via centrifugation. During the process of extraction by shaking the open ends of the tubes must be sealed.
Tubes are manufactured having threaded open end portions on which a cap can be threaded. Although these caps perfect a seal, these tubes and caps can be expensive compared to simple test tubes wherein a plug is used to seal the end portion However, during the shaking and centrifugation operations, the expanding gases within the tube can force the plug out from the tube. The following U.S. Pat. Nos. disclose test tube rack including rack closures Design 215,491 to Pina, issued Sept. 30, 1969, U.S. Pat. Nos. 1,021,998 to Myers, issued Apr. 2, 1912, 1,121,232 to Davis, issued Dec. 15, 1914, 2,784,839 to Omer, Jr., issued Mar. 12, 1957, Design 227,180 to Brodsky, issued Jan. 5, 1973, 3,899,298 to Szczesniaka, issued Aug. 12, 1975, 4,057,148 to Myer et al., issued Nov. 8, 1977, 4,195,059 to Whitcher et al., issued Mar. 25, 1980, 4,240,547 to Taylor, issued Dec. 23, 1980, 4,510,119 to Hevey, issued Apr. 9, 1985, and 2,902,170 to Miller, issued Sept. 1, 1957. The U.S. Pat. Nos. 4,768,653 to Desai et al., issued Sept. 6, 1988 and 4,761,379 to Williams et al., issued Aug. 2, 1988 disclose examples of individual test tubes which include sealing type closure means. None of the aforementioned patents disclose any means for perfecting a seal with the open ends of the plurality of tubes supported in a rack for the purpose of extraction by shaking.
The U.S. Pat. Nos. 3,707,227 to Britt, issued Dec. 26, 1972 discloses a tray package for tubes having a flap which fits within the open end of tubes resting in the contoured bottom of the package. The Britt patent does not relate to means for perfecting a seal with the tubes when they are supported in a test tube rack, in order to provide means for maintaining the seal over the tubes when they are used in the process of liquid/liquid extraction by shaking.
The U.S. Pat. No. 1,143,488 to Bell, issued June 15, 1915 discloses a bottle or tube carrying apparatus including means for sealingly engaging corks in the open ends of the tubes However, the rack is designed merely for storage purposes and is not well adapted for use with a centrifuge or shaking apparatus. Nor does the Bell patent contemplate a single cover which perfects a seal with a plurality of tubes.
The U.S. Pat. No. 3,593,873 to Vonk, issued July 20, 1971 discloses a container for elongated articles, such as tubes, including a plurality of openings for retaining the tubes therein in a cover member including an inner sealing liner for engaging the tops of the tubes. There is no means disclosed in the Vonk patent for clamping the cover on the container and, therefore, the container would be ineffective for sealing tubes during a centrifugation operation.
No prior art reference discloses effective means for sealing tubes that are being shaken and then centrifuged either with or without the use of caps for maintaining the open ends of the tubes in a completely sealed condition. No prior art reference discloses a single rack which can be used for sequential shaking and centrifugation operations without the necessary removal and displacment of tubes during the operations. Further no prior art device provides a single means for sealing all tubes without requiring separate plugs for each tube.